The present invention relates generally to systems for detecting data relating to thermal energy radiated in a scene using infrared radiation image processing.
In particular, the present invention relates to a method of detecting data relating to thermal energy radiated, comprising the steps of:                receiving a sequential plurality of infrared radiation images of the scene, each of said images comprising an array of pixels, each pixel having a value which is representative of a pixel's fraction of the infrared radiation intensity associated with the array of the image;        processing successive images of said sequential plurality of images in order to determine a change in at least one thermal parameter that meets predetermined alarm criteria; and        detecting an event in the scene on the basis of the change determined in the thermal parameter.        
A method of this type, intended in particular for fire detection, is described in US 2003/0132847. According to the method described therein, a region of at least one pixel is determined in an image from a series of images on the basis of the infrared radiation intensity values associated with the pixels, and said region is monitored in several successive images in order to determine a change in said region that meets predetermined alarm criteria.
This known method has the drawback of providing only a two-dimensional representation of the scene and is unable to recognize the position of the objects in the space. This may lead to erroneous evaluations of events; for example, in the case if a heat source of constant dimensions, but arranged on a moving object, for example moving towards one of the infrared radiation sensors, the known method is unable to recognize the approach movement of the heat source, but interprets it as an increase in the dimensions thereof.